Add asset links to GitLab tag

This will allow us to link a release to a file to specific Vagrant Cloud version.
5 jobs for v2020.09.26 in 21 minutes and 42 seconds (queued for 4 seconds)
Name Stage Failure
failed
build:secure Build
du: cannot access 'output/*virtualbox*box': No such file or directory
Uploading artifacts for failed job
Uploading artifacts...
metrics.txt: found 1 matching files and directories

Uploading artifacts as "metrics" to coordinator... ok
id=5107 responseStatus=201 Created token=JCb3gzJ6
Uploading artifacts...
build.env: found 1 matching files and directories

Uploading artifacts as "dotenv" to coordinator... ok
id=5107 responseStatus=201 Created token=JCb3gzJ6
ERROR: Job failed: exit code 1